Day 1, I defined a type foo and a function bar:
Variant foo := A | B.
Definition bar (x : foo) : bool :=
match x with
| A => true
| B => false
end.
Day 2, I modified type foo:
Variant foo := A | C | D.
but forgot to update bar accordingly. However, bar still compiles—it treated B as a wildcard rather than constructor.
Is there an equivalent to “unused parameter” warning for Coq? If no, is it worth adding such warning and suggest replacing pattern B with _?